Casing hanger assembly

Abstract

A casing hanger assembly includes a landing ring secured to a containment well cellar or the conductor pipe. A casing hanger welded to the external surface of the last section of surface casing seats into the landing ring. Optionally, a lock down mechanism can be used to prevent buoyancy and hydraulic forces from causing the well to pack off.

I claim: 
     
       1. A well construction system comprising:
 a) a conductor pipe having an upper portion and installed in a well hole; 
 b) a surface casing having an external surface and a weight and downward force, and extending through the conductor pipe; 
 c.) a surface casing hanger secured by welding to any portion of the external surface of the surface casing, whereby the surface casing hanger and the welding between the surface casing hanger and the surface casing support the weight of the surface casing, and the downward force of the weight of the surface casing is parallel to the external surface of the surface casing; 
 d) a base plate having a first area, the base plate being embedded in a region of the well hole and surrounding said conductor pipe and being attached thereto; 
 e) a landing ring secured to the upper portion of the conductor pipe and the surface casing hanger and having an internal profile for receiving the surface casing hanger to form a casing hanger assembly, whereby the surface casing hanger interacts through the landing ring and conductor pipe to distribute the weight of the surface casing over the first area of the base plate; and 
 f) an upper riser with a lower end feature that mates with and is detachably connected to an external quick connect feature of the landing ring; and 
 wherein the casing hanger assembly further comprises lock down assembly, the lock down assembly comprising a recess in the internal profile of the landing ring and a biased spring and stud assembly attaches to the casing hanger and, when the stud engages the recess, configured to secure the surface casing hanger and prevent the surface casing from being pushed upwardly by forces selected from a group consisting of buoyancy forces and hydraulic forces. 
 
     
     
       2. The well construction system of  claim 1  wherein the base plate comprises a structural, load-bearing floor portion of a sealed well cellar, the sealed well cellar collecting well fluids and preventing the fluids from polluting the region surrounding the well site. 
     
     
       3. A casing hanger assembly for use with a well construction system, the well construction system having a conductor pipe with an upper region, a surface casing with a weight and downward force, an upper end and passing through the conductor pipe, and a wellhead assembly attached to the upper end of the conductor pipe, and the casing hanger assembly comprising:
 a) a landing ring secured to an upper region of the conductor pipe, as by welding; 
 b) a surface casing hanger which engages and is supported by the landing ring; the surface casing attached by welding at any portion of the upper region of the surface casing to and supported by said surface casing hanger, whereby the surface casing hanger and the welding between the surface casing hanger and the surface casing support the weight of the surface casing, and the downward force of the weight of the surface casing is parallel to the upper region of the surface casing; and 
 c) a lock down assembly, the lock down assembly comprising a recess in the internal profile of the landing ring and a biased spring and stud assembly attaches to the casing hanger and, when the stud engages the recess, configured to secure the surface casing hanger and prevent the surface casing from being pushed upwardly by forces selected from a group consisting of buoyancy forces and hydraulic forces. 
 
     
     
       4. The casing hanger assembly of  claim 3  wherein the landing ring includes an external quick connect feature that is configured to mate with and detachably connect to a lower end feature of an upper riser.